The invention relates to a dental instrument with a tool for treating teeth, the tool being fixed in a gripping shaft and is also removable therefrom.
Dental instruments for manually working on teeth are known in numerous different forms. In the simplest constructional embodiment the dental instrument is constituted by a single piece formed by a gripping shaft and a tool. As it is necessary to use tools of different shapes and sizes when treating teeth, it is necessary to have a correspondingly large number of instruments. These instruments also include those in which although the gripping shaft and tool are constituted by two parts, said parts are not detachably joined together.
In addition, two-part dental instruments are known, in which the gripping shaft and tool are interconnected in a detachable manner, either manually or by using a wrench. In the first embodiment the connection is brought about by a collet, which requires additional securing against the tool twisting. By turning a sleeve it is possible to fix or release the tool with respect to the gripping shaft. Thus, the tool can be replaced without difficulty if breakage occurs of it becomes worn.
This also applies with respect to the second embodiment, in which onto the base part of the tool are shaped a taper sleeve and to the latter a threaded bolt. The taper sleeve and threaded bolt can be screwed into a tapped hole provided in the gripping shaft with a taper shaped onto the mouth of the hole and can be fixed with a wrench. This solution also makes it possible to replace the tool without difficulty.
As it is an unavoidable requirement of dental instruments of the aforementioned type that the gripping shaft and the tool are reliably interconnected, so that in part very considerable force exerted when treating the teeth, particularly in the direction of the shaft axis and in the circumferential direction, can be applied without any relative movement between the gripping shaft and the tool. Thus, the instrument with the collet requires an additional securing means to prevent twisting and the other instrument requires a securing cone or tape.